With this camera, at what pioint am I wasting my money buying a faster card?

Brands like SimpleTech, Kingston, and Lexar all have $20 rebates and are generally the same price ($60-$65). SimpleTech says (on the Dell.com website) that their writes to 3Mbps which is 20X. The Lexar for this price range ($65) is 12X.. so it is slower (supposedly) than the cheaper SimpleTech.

Get the cheaper one. The high speed compactflashes can only be taken advantage of by pro cameras. What good is a 3MB/s capable card if the camera can only manage to write at a slow 600KB/s? I remember seeing Kingston 256MB CF very cheap. That's one of the CF's I use as back up (carry on from my previous digital camera).